Method of sewing shoes



Aug. l, 1950 J. P. FREDERICKSEN 2,517,103

METHOD OF SEWING SHOES Original Filed April 6, 1946 3 Sheets-Sheet 1 Aug. 1, 195o J. P. FREDERICKSEN METHOD 0F SEWING SHOES 3 Sheets-Sheet 2 Original Filed April 6, 1946 Allg 1 1950 J. P. FREDERICKSEN 2,517,103

METHOD oF SEWING sHoEs Original Filed April 6, 1946 3 Sheets-Sheet 3 Patented Aug. 1, 1950 UNITED STATES PATeNT OFFICE ME'EHQD 1 0E `SEWING SHOES .lames P, Fredericksen, Braintree, Mass., assignor f to `United ShoeMachinery Corporation, Flemin'gton, N. J., a corporation of New .Hersey (rilgrinal` application April 6, 1946, Serial No.

660,233. `Dvidedand this ber c, 19u-,separan 790,111

cation for United States Letters Patent Serial No. 6160233, filed April 6, 1946, in the` name ofthe present inventor, of which application the present application isa division.

In the practice of the invention advantage is taken of certain heretofore unappreciated qualities of recently developed types ofthreadsm'ade of synthesized plastic fibers, such qualities `including extraordinary extensibility and a peculiar after any stretching force which has been exerted upon the thread is reduced.

ABecause of' these characteristics, which differ greatly from those oiv cotton or linen thread, these new threads cannot be used satisfactorily in, for example, the conventional inseam and outsole sewing machines as employed in cmnmercial` shoe manufacture with cotton or linen thread, but it has been discovered that, by establishing a new relation between certain of the thread handling parts of such machines and changing their action in certain respects, the synthetic liber thread not onlycan" be used successful-ly but seams can be made having new and unexpected characteristics 'which rende-r thesewed article definitely superior to similar articles as heretofore made.

The invention consists in the novell features hereinafter fully disclosed and described in their various aspects in connection" with the accompanying drawings, in which Fig. l is a sectional view, illustrating the principal parts of" a shoe sewing machine adapted for use in carrying out the present invention,` together with a portion of a shoe upon which the method ofthe invention is being performed, the parts of the machine being indicated in positions taken after the needle haswbeen retracted during the iormationof a stitch;

Fig. vZis adetail plan view of a portionof a shoe being presented to themachine, withthe machine" parts4 in the positions of Fig. l;

Fig. 3 is a view"` similar to Fig. l, with portions of the frame omitted and with parts in positions assumed directly after a stitch is set;

Fig. l is adetai-l plan View of a portion of a` shoepresented to themachine with the parts in the positions shown in Fig. 3;

application Deceni- (Cl. 12s-+142) Fig. 5 is a sectionalview of a portion of ashoe, illustrating the relations between the parts inimediately after a seam has been inserted;

Fig. 6 is a similar view of a portion of a sewn shoe, illustrating the condition of the seam after an extended period off time has elapsed;

Fig. 7 is a detail diagrammatic view of altension wheel, illustrating the action when rela;- tively inextensible sewing thread is employed in the machine of Fig. 1;

Fig. 8 is a time chart, illustrating the 'improved manner of operation of the machine, with al comparison between the action occurring when linen thread under normal operating conditions is employed and when a specially prepared thread, such as nylon, is employed;

Fig. 9 isa characteristic stress-strain diagram, comparing linen, cotton and nylon threads; and

Fig. lOlis a sectional view taken along the line X-Xof Fig. 1, showing a portion oi the tension brake actuating mechanism. l

The method of the present invention is illustrated as employed in the manufacture oi a Goodyear welt shoe in which `a sole member is permanently attached to an upper by an inseam the stitches of which are under heavy tension approaching the breaking strength of the thread employed, to bring the parts into close conformity with a `last on which they Vare mounted; The inseam sewing operation thus supplements the lasting operation in stretching the upper over` the last and in giving it its final tension to bring it into close-fitting relationship with the surfaces of the last.` Because of the heavy tension required in the thread to bring the parts together, 9a heavy thread is customarily employed, having a diameter sometimes approximating onesixteenth of an inch in its largest sizes, commonly designated as 1`2 or lll-cord thread.V In some instances, for lighter weight shoe manufacurte, smaller sizes of thread are employed but, in any case, a tension is exerted which is heavy for thread of the size being used.

Referring to Figs. 5 and 6 of the drawings, a Goodyear welt inseam is illustrated by a section taken through a shoe. The shoe is ready for in seam sewing after the upper, indicated at 2, has

l which is indicated at 8, passing through the rib andthe marginal portion ci the upper 2. The ribn of the insole projects substantially at vright anglesto the general plane of the insole and is setback a short distance from theedge ofthe" insole, providing a feather on the insole which" forms an angle of slightly more than 90 with the the upper and a chain-stitch inseam l2 is formed l with the stitches entering the groove of the welt and passing through the upper, the exposed' threads appearing on the welt and in the angular channel between the insole rib and the upper surface of the insole inside the rib. It is the practice to insert the inseam as close to the upper surface of the insole as is practicable so that the stitches act to draw the bridged upper securely into the angle between the rib and the feather of the insole. j

With extremely heavy work, such as that found in military footwear, it is difficult if not impossible to bring the upper, bridged from the staples in the rib to the feather on the insole, closely into conformity with the angle between the two parts of the insole. This diiculty is increased by the resistance of the welt to bending along the line of the groove therein, such resistance adding to the tension in the thread necessary to break the materials down into the angle of the insole. When the materials are insufficiently broken down, there is a void space, indicated at I4, between the upper and the angle of the insole. In many instances, the thread is ruptured before conformity is obtained or, where the substance of the rib, upper or welt is weak, the thread will cut through the parts before closing the void space.

The next operations on the shoe are the inseam trimming, during which the upper portion of the sewing rib, including the staples 8, is cut.

off close to the inseam, and the welt beating operation for flattening the remaining portions of the rib, upper and welt more closely together against the bottom of the last. The welt beating operation assists in some degree in filling up the void space Ill but, at best, it is only an expedient. After the shoe is completed by attachment of an outsole to the welt Ul and the last is removed from the shoe, the forces exerted upon the inseam during wear of the shoe will cause the inseam, when linen or cotton thread is used, to open up between the welt and upper, exposing the inseam thread to entry of moisture and other destructive agents and constituting a weakness in the construction of the shoe which reduces its effective life, besides giving it an unattractive ap pearance. f

Even underthe best conditions, with extreme tension in the thread, the shoe parts are compressed somewhat by the thread but, because of a peculiar characteristic of delayed compressibility found in all leather, full compression is not obtained in the parts until an appreciable length of time has elapsed after each stitch is inserted. Thus, even though a tension be applied to the thread of an intensity close to its breaking strength in setting each stitch, the tension thereafter becomes gradually reduced as the leather yields comparatively slowly to the pressure of the thread. In some instances, with inextensible thread, after the work yields, the tension may be reduced to a small fraction of that employed to set the stitch within a few minutes after the seam has been sewn. If the thread itself does not have sufficient contractility to take up the compression of the parts operated upon, there 4 will be no possibility of closing up void spaces, such as that indicated at I4.

Cotton and linen threads now in general use, and having elongation and contraction of only from three to ten per cent, do not follow up the compression of heavy leather or similar stiff substances, of a thickness substantially greater than the diameter of the thread, sulliciently to hold the materials together securely and tightly.

In the shoe constructed by the method of the` present invention, even if the seam after being inserted has insufficient tension to draw the parts together without void spaces such as indicated at I4, the thread employed is so composed and treated, as will be explained, that it will have sufficient elasticity or contractility to close up such spaces while the shoe is retained on the last and will maintain the parts securely in contact after the void spaces are closed up, with a firm seating throughout the area of contact. The tightening action due to contraction of the thread takes place within a few hours of the time the l seam is inserted and is of an extent greater than will be maintained securely and firmly together,

without danger of separation under the stress of Wear, for a time far in excess of that required to wear out the leather in the shoe, with the result that no opportunity is provided for entry of deteriorating agents into vital points of the shoe structure.

Examples of materials which can be utilized successfully as sewing threads in the manner outlined above are synthetic, fiber-forming materials such as nylon (polyamide resin of proteinlike structure), rayon (cellulose base materials), vinylidene or Vinyon (polymerized vinyl compound), or the like, given the proper mechanical working and heat treatment after either formation of the basic ber or of the completely spun thread.

To assist in orientation of the molecules and to reduce as much as possible the tendency of sewing threads to stretch while in use, substantially all such fiber-forming materials `from which they are composed are ordinarily at some time during 'their manufacture subjected to heat and mechanical stretching treatment, frequently accompanied by the application of chemicals. Stretch.- ing treatment also strengthens the threads composed of such bers until eventually they display characteristics of strength and durability in the maximum possible degree.

According to this invention, instead of car- `rying out the stretching treatment in such threads to an ultimate maximum as usual, the

stretching is terminated substantially before thatv the fibers to become elongated somewhere within the range of from twenty to fifty per cent before breakage. Thus, if such a thread is employed for shoe inseam sewing operations, suilcient strength is retained in the thread to retain the shoe parts in assembled relation, while at the same time the ability to contract after a stitch setting.ten.

sion has beenreleased is sufcient to close up any void spaces left betweer''f the parts during the sewing operation, as welt as toroffset the compressibility of the parts after the seam has been inserted.

In order to insert an inseam connecting the welt,` upper and insole of a Goodyear weltshoe, using' specially treated highly contractile thread of the type employed in theshoe construction herein described, it has been found unnecessary to exert such heavy tensions duringsewingas are used in the formation of the usual i-nseamin which commercial linenor cotton threads are employed. It is only essential to applyl to such specially treated thread while each stitch is being set sufficientK initial tension to `stretch the thread to such a degree thatits subsequent contraction will draw the parts securely and iirmly` together while the shoe is on the last and the delayed compression or the parts will be wholly oi'set,u so as to prevent substantial `release oftension -in the threadl after the seam is formed" and the last is removed from the shoe. rlhus, it becornesA possible to reduce thefinitial` stitch setting tension in the threadjsubstantially below the intensity which will draw the shoe parts securely and firmly together immediately at the time the stitch` is.` set. Furthermore, after setting each stitch, the initial: tension is retained in the stitch without permitting slippage ofthe thread through the substance of 4the shoe parts r such release as willcause substantial loosening of that stitch after being set or while the succeeding stitch is being formed.

With a reduced initial stitch setting tensionJ also, the tension maymore readily be controlled' uniformly from one stitch to another than. with higher initial tensions, the only requirement be ing a retention of sufficient residual contractility in the thread 'to draw and maintain the parts into firm. contact with each other after the seam is inserted. Moreover, it is nolonger necessary. to apply a lubricant or hot wax to `the thread to insure uniform tightening action ofthe stitches o during sewing operations.

For; performing the method of the` invention illustrated herein amachine has been provided of a type similar in some respects to that ofi` the inseam shoe sewing machine disclosed in United States Letters Patent No. 1,030g743., granted June 25, 15212,` upon application of-` William C. Meyer., andNo.. 1,108,560', granted` August 25, 191,4, upon an application of Andrew Eppler. The stitch forming devices comprise curved hook needle 1,6, a looper i8, a thread linger 20, a. main takeup 22;` an auxiliary take-.up 24n and a frictionally retarded rotary thread' tension wheel 25'. The needle I6 oscillates about a stud -Z'tt toward' and from the work, entering the groove in 'the welt,

passing through the portion of the upper which` is bridged across between the sewing rib andthe feather on the insole, and nally` penetrating the baseof the sewing rib to receive the thread with-` in its hook from the looper; The thread linger thereafter acts to hold aside a portion oifthreado iliary take-up is pressed downwardly continuousand acted upon along its straight upper surfacel by a pair oi adjustable abutments Ell and 52.

The abutments 5t` and 52 `are slidingly mounted on a pair of individually spring-pressed actuating levers 5t and t6, respectively. To adjust the tension on the, thread, the abutments have threaded openings to receive adjusting screws 58 provided with suitable knurled heads rotatable in the levers.` The actuating levers 5ft and ofor the brake shoe esl are pivotally mounted at their rearward ends on a stud` in the frame of the machine and, at their forward ends, the levers are forced downwardly by a vertical tension rod t2 slidingly mounted in a perforated nxed lug 64 at, its lower end and arranged to bear against a short arm 56 serving `as a balancing member to distribute the downward pressure at the lower end of the rod t2 equally against the actuating levers 5t and 56. The upper end of the tension rod carries a tension wheel brake spring Sti conipressed between an adjustable collar 'lt clamped to the rod 52- and a perforated arm or a governoractuated lever l2, through the perforation of which the upper end of the rod G2 passes loosely.

The manner of' operation of the conventional rnachine` of this type using `a substantially inextensible thread composed or" either linen or cotton will now be described. Referring to Fig. 8 of the drawings, it is apparent that the talee-up stroke of the take-up occurs between and 125 of rotation -of the main sewing shaft while the needle engages the work, or during less than one sixth of the time in each complete sewing cycle. Assuming that the machine is operating at a speed of 69o cycles per minute or l0 cycles per second, the take-up stroke of the take-up occurs within one sixtieth of a second. rllhe major portion of the active stroke of the take-up is utilized in taking up the slack in the thread so that only a small portion (approximately 25 main shaft rotation) of the take-up stroke, indicated at i3, actually can cause thread to be pulled past the tension wheel, the brake tft resisting rotation of the tension wheel at other times. It can be assumed, therefore, that the velocity of inextensible linen thread as it is being pulled past the tension wheel ranges upwardly to an amount of inchesl per second maXimum. At` this velocity, the tension wheel is rotated so rapidly that there is provided a substantial surplus of thread between the tension wheel and the worin as a result of overthrow caused by failure of the brake t2 to bring the tension wheel to rest the exact instant at which the tension on the thread is released. On account of variations in mechanical adjustments and conditions of the world the surplus in the amount, of theread drawn past the tension wheel during each stitch varies substantially from one sewingV cycle to another. To reduce this variation of surplus thread in the machine of the Eppler patent, the pressure on the tension wheel brake is increased in each sewing cycle in a manner set forth in United` States Letters Patent No. 2,424,991," granted on August 5, 194W,` upon an ap plicationof Henry A.4 Landroche by actuating the spring-pressedl lever 56 `to bring the `abutment 52 into engagement with the brake supporting lever Mi. During the take-up stroke of the talreup, the tension on the thread thus is increased, as indicated by the line labeled Friction increase in Fig. 8, and the auxiliary take-up is moved against the stop screw i4. As soon as a stitch is set and the take-up completes its stroke, the friction is again decreased to enable easy withdrawal of thread if necessary for the succeeding stitch formation. Decrease in friction is obtained by raising the -abutment 52 from the lever 46 to a position indicated in Figs. 1 and lo. During the time the friction is decreased, the needle is looped and is retracted to the position of Fig. l, with the loop of thread carried in its hook. At this time, the take-up is giving up thread to the needle so as to provide little or no tension in.

the thread which will resist the retracting movement of the needle. If any substantial degree of tension exists at this time, the auxiliary take-up 24 yields a short length of thread, being raised slightly against the force of the plunger 34 before causing any rotation of the tension wheel.

Except during the needle looping and retracting operations and the stitch setting action, with the use of inextensible cotton or linen thread, the auxiliary take-up is arranged to maintain an intermediate position between a pair of motion-limw iting stops, comprising a set screw 'M threaded into the machine frame and a block 'i6 screwed to the machine frame, which block may be engaged by a set screw 18 passing through the auxiliary take-up. With proper adjustments of the auxiliary take-up for relatively inextensible thread, the reduced frictional force on the tension wheel usually is sufficient after setting each stitch to prevent slippage or other movement of thread in the substance of the work during formation of the succeeding stitch, into the set stitch, as will effect a substantial release of tension in that stitch. However, in some instances, the thread may slip through the substance of the work sufficiently to cause excessive looseness in spite of the high degree of tension applied to the thread by the increase of pressure on the tension wheel brake while setting each stitch. In the latter instance, the resulting seam will be faulti from looseness.

The mechanism for engaging and disengaging the abutment 52 from the brake supporting lever ll is more fully described in the said Landroche patent. Briefly, this mechanism includes a pin 8l] engaging the underside of the forward end of the actuating lever 55 and projecting laterally from a pivotally mounted block 82 having a recess within which a tooth-shaped projection 84 is mounted upon a lever 86 fulcrumed on a shaft 88 fixed in the machine frame and, at its forward end, the lever carries a roll 9u engaging a cam 92 on the sewing shaft 32,

As thus far described, the machine is substantially the same as in the patents above referred.

to. The elongation or extensibility of linen and cotton threads now in common use is illustrated in Fig. 9, in which the comparable characteristic stress-strain curves, correspondingly labeled, are indicated. Linen has an elongation before breakage of not substantially more than three per cent, whereas cotton may become elongated three times this amount before breakage. Cotton, however, is not as strong as linen and, consequently, the actual tension is less in the stitches formed of cotton thread since the adjustments required for cotto-n thread in the machine are such that a lower braking pressure is applied to the tension 8 wheel brake drum'42. In any event, the amount of linen or cotton thread taken up by the take-up is suicient to cause the major portion of each thread length required per stitch to be pulled suddenly past the tension wheel against the relatively heavy tension directly after each stitch is set.

The rotation of the tension wheel with inextensible linen or cotton thread is indicated in Fig,

8 by the line designated Linen During the time the threaded needle is retracting from the work with a loop of thread to be employed in the formation of the succeeding stitch, a small further amount of thread may be pulled 01T the supply and drawn past the tension Wheel if insufficient thread is provided by the auxiliary takeup. In some instances, this small further amount of thread is drawn past the tension wheel at some .l .portion of the sewing cycle other than during the i sewing shaft, as explained above.

ings being one third actual size.

needle retracting stroke, depending upon adjustments.

An illustration of the relative proportions of tension wheel rotation while the machine is being operated with threads of different materials is given in Figs. 3 and '7 which show the relative amounts of thread drawn past the ten-sion wheel while the needle is being retracted and while the take-up is setting that stitch. In Fig. 7, the amount of linen or cotton thread drawn past the tension wheel is assumed tobe an inch and a quarter length for each stitch, which corresponds to the total amount of tension wheel rotation between the lines $14 and 96, the scale of the draw- During that portion of tension wheel rotation between the lines 54 and 98, the frictional braking pressure applied to the tension wheel is increased, for instance, to an amount requiring a steady pull of fifteen pounds on the thread during the take-up stroke of the take-up. Thus, the major portion of the total thread is drawn past the tension wheel during the take-up action in substantially less than a sixth of the complete rotation of the The major portion of linen or cotton thread for each stitch, accordingly, may be drawn past the tension wheel in less than 25 of the sewing shaft rotation, necessitating sudden, jerky and irregular rotation of the wheel with consequent non-uniform lengths of thread being measured for successive stitches. During the remaining 335 of sewing shaft rotation, including the time of the needle retracting stroke, a small portion of the thread required in a succeeding stitch is drawn past the tension wheel under a decreased frictional braking pressure, as indicated by the angular distance between the lines 98 and 96.

A feature of the present invention includes substituting, in place of linen or cotton thread, the specially treated synthetic, liber-forming plastic thread of the type hereinbefore referred to, to avoid the necessity of drawing past the tensio-n wheel the major portion of total thread required in forming a sitch during a small part of the take-up stroke. As above explained in connection with Fig. 7 in the drawings, the amount of thread drawn past the tension wheel during the take-up stroke of the machine, according to the present sewing method, is limited to a very short length while the remainder of thread required in forming a stitch is drawn past the tension wheel gradually throughout the rest of each sewing cycle after the take-up stroke has been completed or through approximately 335 of the complete sewing shaft rotation without releasing the tension and accordingly a. tension wheel brake spring of a greater strength is required to make up for f inertia effects.

With the adjustments thus made, the auxiliary take-up 24 acts as a stitch setting tension limiting device (see Fig. 3). Also, the action of the auxiliary take-up is such as to reduce still further the rotation required of the tension wheel during the stitch setting operation by giving up a short length only of thread during the stitch setting stroke of the take-up. It also prevents sudden, excessive strains in the nature of impacts on the thread under stitch setting tension and distributes the time of tension wheel rotation over a longer period so that a slower continuous rotation of the tension wheel results.

With the avoidance of sudden high-speed intervals of tension wheel rotation and a reduction in intensity of suddenly applied strains on the thread and correspondingly in the machine itself, a smoother sewing operation is produced with greater uniformity both in formation and in setting of successive stitches in a seam. Also, the moving parts of the machine and the bearing surfaces are less subject to damage from excessive impacts so that less attention is needed on the part of the operator in maintaining proper operation of the machine. A sewing machine operated in this manner, consequently, is able to operate over a longer period of time and with fewer adjustments than heretofore. Furthermore, the seam inserted actually is of a. superior nature in that the threads continue to contract as the substance sewn yields and to draw the parts more tightly together for a substantial period of time after seam insertion.

Thus, in the case of the inseam in a shoe, the

diiiculties formerly encountered are overcome in the manner hereinbefore set forth. In some instances where the upper of a shoe has been already tightened roughly about a last, it is possible by the use of the present method of operation to tighten the upper sufciently by means of the contracting thread to eliminate the necessity of a separate lasting operation.

The improved action of the thread to produce a tight seam of superior nature in sewing sole leatheris an evidence that the invention is present or'being practiced, particularly when a` seam first inserted showsincomplete tightening of the parts sewed, one against the other, andwhen, after a lapse of time, the parts are drawn much closer together. Also, an advantage of the present invention is apparent when the use of a. liquid lubricant or hot wax on the thread is found unnecessary to effective insertion of la tight seam in sole leather, the ability of the thread to stretch and contract being far `beyond the range of similar qualities in threads: previously employed for such purposes. v

The ability of the thread to contract in the manner outlined is due in part to treatment and elongation of the thread prior to its use;v In certain instances, the contractility is enhanced after a seam has been inserted by the presence of moisture in the sole leather or the action of tannin or the presence of other common astringent chemicals brought vinto contact with the thread.

The nature and scope of the invention having been indicated and a particular manner of carrying out the invention having been described, what is claimed is:

That improvement in methods of making shoes which comprises assembling a sole member and an upper upon a last, providing an elastic thread of ber-forming material treated to insure substantial residual contractility after a stitch setting tension is applied, inserting a seam of said thread connecting the sole member and upper With stitches having insufficient tension in the thread during the formation of the stitches to bring the parts rmly together but' having sumcient resid-ual contractility to draw the parts together after the seam is inserted, and retaining the shoe on the last until the thread in the stitches contracts sufciently to bring the upper into accurate conformity with the shape of the last before removing the last from the shoe.

JAMES P. FREDERICKSEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 4 Date 

